This invention relates to an exposure device for forming an image on a sensitized element by means of light transmitted through a shutter unit provided with shutter elements adapted to selectively open and close.
Conventionally, a liquid crystal display panel has been adopted as one of the above shutter units, which generally includes multiple liquid crystal elements spaced at certain intervals. The liquid crystal elements are each adapted to open and close in response to certain picture image informations. Backlighting the panel thus configured develops an image displayed on the panel. For reproducing the image displayed on this panel, there has so far been a condensing lens disposed between the panel and the sensitized paper so that the image on the panel has been formed on the sensitized paper by way of the lens.
In such an arrangement as described above, the panel has been constantly fixed relative to the sensitized paper with no relative mobility. Consequently, the problem has been such that the resolution of the image could never surpass that obtained by the outer dimension of the light transmission area of each of the liquid crystal display elements forming the panel.
Further, the sensitized element is placed close to the image forming side of the shutter unit at a certain small distance therefrom, and there is no means provided between the image forming side of the shutter unit and the sensitized element. Accordingly, when the light source is turned on with both side elements of adjacent three elements kept open, and center element thereof kept closed, the light passed through opened shutter elements is allowed to reach not only the underside of the two opened shutter elements kept open but also that of the shutter element kept closed. Also, it may be irregularly reflected between the sensitized element and the underside of the shutter elements to allow some reflections to pass to the underside of the shutter element kept closed, which results in unintended exposure of a corresponding area on the sensitized element. Likewise, the light passed through the surrounding of each shutter element is admitted to the underside of the center shutter element kept closed to expose some area of the sensitized element. This results in an image with its exposed part not clearly delimited from the unexposed part not formed on the sensitized element.
On the other hand, a color recording device for recording images on a sensitized sheet using a color liquid crystal panel is becoming a major subject of studies with a recent outstanding progress in the color liquid crystal display technique. The color liquid crystal panel is composed of a filter placed on a known liquid crystal panel serving as a shutter. The filter consists of three display elements of red (R), green (G) and blue (B) which are equal in size to the picture elements on the liquid crystal panel. A set of these red, green and blue display elements is called a cell which serves as a unit for color display. There are in general two types of color recording device, in one of which the color liquid crystal panel closely adjoins a so-called light/pressure sensitized paper. In the other type of such device, there is a space between the color liquid crystal panel and light/pressure sensitized paper, in which an optical system is interposed to allow images on the color liquid crystal panel to be formed on the sensitized paper. In any such color recording device, the light ray passed through the display elements of each cell of different colors acts upon the sensitive component on the sensitized paper, with the result of a color image developed on the sensitized paper.
However, the following problems are encountered because the resolution of light/pressure sensitized paper is generally higher than that of the color liquid crystal panel. For instance, a uniformly vivid red image formed on the color liquid crystal panel turns to somewhat blackish red rather than bright red when projected and exposed on the sensitized paper. Assuming the light is thrown to a particular cell of the color liquid crystal to obtain a red image, it is passed through the R element so that the area of the sensitized paper corresponding to the R element is exposed to light, while the area corresponding to the G and B elements is not exposed because light is not admitted through them. Consequently, unlike the color liquid crystal panel in which bright red is developed by raising the brightness of red picture element, the one third of the area corresponding to the cell on the sensitized paper is colored red, while the remaining two third area is blackened. As a result, the image formed on the sensitized paper fails to present bright colors as a whole.
Also, if one attempts to create white on the sensitized paper by allowing the light to pass through the filter for all the R, G and B picture elements within the cell, what is available is only a grayish-white image in a color recording device of this nature.